Refactor appendParamsForQueryExecModeExec

Extract logic for finding OID and converting argument to encodable
value. This is in preparation for a future change for better supporting
nil driver.Valuer values.

extended_query_builder.go

@@ -161,58 +161,51 @@ func (eqb *ExtendedQueryBuilder) chooseParameterFormatCode(m *pgtype.Map, oid ui
 // no way to safely use binary or to specify the parameter OIDs.
 func (eqb *ExtendedQueryBuilder) appendParamsForQueryExecModeExec(m *pgtype.Map, args []any) error {
 	for _, arg := range args {
-		if arg == nil {
-			err := eqb.appendParam(m, 0, TextFormatCode, arg)
-			if err != nil {
-				return err
-			}
-		} else {
-			dt, ok := m.TypeForValue(arg)
-			if !ok {
-				var tv pgtype.TextValuer
-				if tv, ok = arg.(pgtype.TextValuer); ok {
-					t, err := tv.TextValue()
-					if err != nil {
-						return err
-					}
-
-					dt, ok = m.TypeForOID(pgtype.TextOID)
-					if ok {
-						arg = t
-					}
-				}
-			}
-			if !ok {
-				var dv driver.Valuer
-				if dv, ok = arg.(driver.Valuer); ok {
-					v, err := dv.Value()
-					if err != nil {
-						return err
-					}
-					dt, ok = m.TypeForValue(v)
-					if ok {
-						arg = v
-					}
-				}
-			}
-			if !ok {
-				var str fmt.Stringer
-				if str, ok = arg.(fmt.Stringer); ok {
-					dt, ok = m.TypeForOID(pgtype.TextOID)
-					if ok {
-						arg = str.String()
-					}
-				}
-			}
-			if !ok {
-				return &unknownArgumentTypeQueryExecModeExecError{arg: arg}
-			}
-			err := eqb.appendParam(m, dt.OID, TextFormatCode, arg)
-			if err != nil {
-				return err
-			}
+		oid, modArg, err := eqb.oidAndArgForQueryExecModeExec(m, arg)
+		if err != nil {
+			return err
+		}
+
+		err = eqb.appendParam(m, oid, pgtype.TextFormatCode, modArg)
+		if err != nil {
+			return err
 		}
 	}
 
 	return nil
 }
+
+func (eqb *ExtendedQueryBuilder) oidAndArgForQueryExecModeExec(m *pgtype.Map, arg any) (uint32, any, error) {
+	if arg == nil {
+		return 0, arg, nil
+	}
+
+	if dt, ok := m.TypeForValue(arg); ok {
+		return dt.OID, arg, nil
+	}
+
+	if textValuer, ok := arg.(pgtype.TextValuer); ok {
+		tv, err := textValuer.TextValue()
+		if err != nil {
+			return 0, nil, err
+		}
+
+		return pgtype.TextOID, tv, nil
+	}
+
+	if dv, ok := arg.(driver.Valuer); ok {
+		v, err := dv.Value()
+		if err != nil {
+			return 0, nil, err
+		}
+		if dt, ok := m.TypeForValue(v); ok {
+			return dt.OID, v, nil
+		}
+	}
+
+	if str, ok := arg.(fmt.Stringer); ok {
+		return pgtype.TextOID, str.String(), nil
+	}
+
+	return 0, nil, &unknownArgumentTypeQueryExecModeExecError{arg: arg}
+}